A Monte-Carlo trial on the behaviour of the non-additivity test with nonnormal data

Abstract

SUMMARY The behaviour of the t test based on Tukey's one degree of freedom for non-additivity is investigated by a small Monte-Carlo trial on two types of nonnormal data. As is to be expected, the levels of significance are considerably exaggerated when there are no real additive effects, but there is no serious disturbance when additive effects are introduced. The implication of these findings in the various contexts in which the test may be used are discussed.